Tantalum silicon oxynitride high-k dielectrics and metal gates

ABSTRACT

Electronic apparatus and methods of forming the electronic apparatus include a tantalum silicon oxynitride film on a substrate for use in a variety of electronic systems. The tantalum silicon oxynitride film may be structured as one or more monolayers. The tantalum silicon oxynitride film may be formed using a monolayer or partial monolayer sequencing process. Metal electrodes may be disposed on a dielectric containing a tantalum silicon oxynitride film.

RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.12/855,556, filed Aug. 12, 2010, which is a Divisional of U.S.application Ser. No. 11/514,601, filed Aug. 31, 2006, now issued as U.S.Pat. No. 7,776,765, both of which are incorporated herein by referencein their entirety.

This application is related to the commonly assigned applications U.S.application Ser. No. 10/229,903, entitled “ATOMIC LAYER DEPOSITED HfSiONDIELECTRIC FILMS,” filed on 28 Aug. 2002, now issued as U.S. Pat. No.7,199,023; U.S. application Ser. No. 11/216,474, entitled “LANTHANUMALUMINUM OXYNITRIDE DIELECTRIC FILMS,” filed on 31 Aug. 2005, now issuedas U.S. Pat. No. 7,410,910; U.S. application Ser. No. 11/355,490,entitled “CONDUCTIVE LAYERS FOR HAFNIUM SILICON OXYNITRIDE FILMS,” filedon 16 Feb. 2006, now issued as U.S. Pat. No. 7,709,402; U.S. applicationSer. No. 11/010,529, entitled “ATOMIC LAYER DEPOSITED LANTHANUM HAFNIUMOXIDE DIELECTRICS,” filed on 13 Dec. 2004, now issued as U.S. Pat. No.7,235,501; and U.S. application Ser. No. 10/352,507, entitled “ATOMICLAYER DEPOSITION OF METAL OXYNITRIDE LAYERS AS GATE DIELECTRICS ANDSEMICONDUCTOR DEVICE STRUCTURES UTILIZING METAL OXYNITRIDE LAYER,” filedon 27 Jan. 2003, which applications are incorporated herein byreference.

This application is also related to the following patent applicationsfiled on Aug. 31, 2006; U.S. application Ser. No. 11/514,655, entitled“ATOMIC LAYER DEPOSITED TANTALUM ALUMINUM OXYNITRIDE FILMS”, now issuedas U.S. Pat. No. 7,759,747; U.S. application Ser. No. 11/514,533,entitled “ATOMIC LAYER DEPOSITED SILICON LANTHANIDE OXYNITRIDE FILMS”,now issued as U.S. Pat. No. 7,432,548; U.S. application Ser. No.11/515,143, entitled “ATOMIC LAYER DEPOSITED HAFNIUM LANTHANIDEOXYNITRIDE FILMS”, now issued as U.S. Pat. No. 7,563,730; U.S.application Ser. No. 11/514,545, entitled “ATOMIC LAYER DEPOSITEDTANTALUM LANTHANIDE OXYNITRIDE FILMS”, now issued as U.S. Pat. No.7,544,604; U.S. application Ser. No. 11/498,578, entitled “DEPOSITION OFZrAlON FILMS”, now issued as U.S. Pat. No. 7,727,908; U.S. applicationSer. No. 11/515,114, entitled “ATOMIC LAYER DEPOSITED HAFNIUM TANTALUMOXYNITRIDE FILMS”, now issued as U.S. Pat. No. 7,605,030; and U.S.application Ser. No. 11/514,558, entitled “ATOMIC LAYER DEPOSITEDHAFNIUM ALUMINUM OXYNITRIDE FILMS”, which patent applications areincorporated herein by reference.

TECHNICAL FIELD

This application relates generally to semiconductor devices and devicefabrication and more particularly, devices having a high-K dielectric.

BACKGROUND

The semiconductor device industry has a market driven need to reduce thesize of devices used in products such as processor chips, mobiletelephones, and memory devices such as dynamic random access memories(DRAMs). Currently, the semiconductor industry relies on the ability toreduce or scale the dimensions of its basic devices. This device scalingincludes scaling a dielectric layer in devices such as, for example,capacitors and silicon-based metal oxide semiconductor field effecttransistors (MOSFETs), which have primarily been fabricated usingsilicon dioxide. A thermally grown amorphous SiO₂ provides anelectrically and thermodynamically stable material, where the interfaceof the SiO₂ layer with underlying silicon provides a high qualityinterface as well as superior electrical isolation properties. However,increased scaling and other requirements in microelectronic devices havecreated the need to use other materials as dielectric regions in avariety of electronic structures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of an atomic layer deposition system forprocessing a tantalum silicon oxynitride film.

FIG. 2A shows a flow diagram of features of an embodiment for forming atantalum silicon oxynitride film using atomic layer deposition andnitridization.

FIG. 2B shows a flow diagram of features of an embodiment for formingtantalum silicon oxide using atomic layer deposition for nitridizationto a tantalum silicon oxynitride film.

FIG. 3 shows a flow diagram of features of an embodiment for forming atantalum silicon oxynitride film using atomic layer deposition andoxidation.

FIG. 4 shows a flow diagram of features of an embodiment for formingtantalum silicon oxynitride film using atomic layer deposition andannealing.

FIGS. 5A-5E illustrate an embodiment of a process for forming a metalsubstituted electrode.

FIG. 6 illustrates a flow diagram of features of an embodiment of ametal substitution technique.

FIGS. 7A-7D illustrate an embodiment of a process for forming a selfaligned conductive layer.

FIG. 8 illustrates an embodiment of a method for forming a self alignedmetal gate on high-K gate dielectrics containing a tantalum siliconoxynitride film.

FIG. 9 illustrates a wafer containing integrated circuits having atantalum silicon oxynitride film.

FIG. 10 shows an embodiment of a transistor having a dielectric layerincluding a tantalum silicon oxynitride film.

FIG. 11 shows an embodiment of a floating gate transistor having adielectric layer including a tantalum silicon oxynitride film.

FIG. 12 shows an embodiment of a capacitor having a dielectric layerincluding a tantalum silicon oxynitride film.

FIG. 13 depicts an embodiment of a dielectric layer having multiplelayers including a tantalum silicon oxynitride layer.

FIG. 14 is a simplified diagram for an embodiment of a controllercoupled to an electronic device having a dielectric layer including atantalum silicon oxynitride film.

FIG. 15 illustrates a diagram for an embodiment of an electronic systemincluding devices with a dielectric film including a tantalum siliconoxynitride film.

DETAILED DESCRIPTION

The following disclosure refers to the accompanying drawings that show,by way of illustration, specific details and embodiments. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the present invention. Other embodiments may beutilized and structural, logical, and electrical changes may be madewithout departing from the scope of the invention. The variousembodiments are not necessarily mutually exclusive, as some embodimentscan be combined with one or more other embodiments to form newembodiments.

In the following description, the terms wafer and substrate may be usedinterchangeably to refer generally to any structure on which integratedcircuits are formed and also to such structures during various stages ofintegrated circuit fabrication. The term substrate is understood toinclude a semiconductor wafer. The term substrate is also used to referto semiconductor structures during processing and may include otherlayers that have been fabricated thereupon. Both wafer and substrateinclude doped and undoped semiconductors, epitaxial semiconductor layerssupported by a base semiconductor or insulator, as well as othersemiconductor structures well known to one skilled in the art. The termconductor is understood to generally include n-type and p-typesemiconductors and the term insulator or dielectric is defined toinclude any material that is less electrically conductive than thematerials referred to as conductors. The following detailed descriptionis, therefore, not to be taken in a limiting sense.

To scale a dielectric region to minimize feature sizes to provide highdensity electronic devices, the dielectric region should have a reducedequivalent oxide thickness (t_(eq)). The equivalent oxide thicknessquantifies the electrical properties, such as capacitance, of adielectric in terms of a representative physical thickness. t_(eq) isdefined as the thickness of a theoretical SiO₂ layer that would berequired to have the same capacitance density as a given dielectric,ignoring leakage current and reliability considerations.

A SiO₂ layer of thickness, t, deposited on a silicon surface will have at_(eq) larger than its thickness, t. This t_(eq) results from thecapacitance in the surface on which the SiO₂ is deposited due to theformation of a depletion/inversion region. This depletion/inversionregion can result in t_(eq) being from 3 to 6 Angstroms (Å) larger thanthe SiO₂ thickness, t. Thus, with the semiconductor industry driving tosomeday scale a gate dielectric equivalent oxide thickness to less than10 Å, the physical thickness requirement for a SiO₂ layer used for agate dielectric may need to be approximately 4 to 7 Å. Additionalrequirements on a SiO₂ layer would depend on the electrode used inconjunction with the SiO₂ dielectric. Using a conventional polysiliconelectrode may result in an additional increase in t_(eq) for the SiO₂layer. Thus, designs for future devices may be directed towards aphysical SiO₂ dielectric layer of about 5 Å or less. Such a smallthickness requirement for a SiO₂ oxide layer creates additionalproblems.

Silicon dioxide is used as a dielectric layer in devices, in part, dueto its electrical isolation properties in a SiO₂—Si based structure.This electrical isolation is due to the relatively large band gap ofSiO₂ (8.9 eV), making it a good insulator from electrical conduction.Significant reductions in its band gap may eliminate it as a materialfor a dielectric region in an electronic device. As the thickness of aSiO₂ layer decreases, the number of atomic layers or monolayers of thematerial decreases. At a certain thickness, the number of monolayerswill be sufficiently small that the SiO₂ layer will not have a completearrangement of atoms as in a larger or bulk layer. As a result ofincomplete formation relative to a bulk structure, a thin SiO₂ layer ofonly one or two monolayers may not form a full band gap. The lack of afull band gap in a SiO₂ dielectric may cause an effective short betweenan underlying electrode and an overlying electrode. This undesirableproperty sets a limit on the physical thickness to which a SiO₂ layercan be scaled. The minimum thickness due to this monolayer effect isthought to be about 7-8 Å. Therefore, for future devices to have at_(eq) less than about 10 Å, other dielectrics than SiO₂ need to beconsidered for use as a dielectric region in such future devices.

In many cases, for a typical dielectric layer, the capacitance isdetermined as one for a parallel plate capacitance: C=κ∈0A/t, where κ isthe dielectric constant, ∈0 is the permittivity of free space, A is thearea of the capacitor, and t is the thickness of the dielectric. Thethickness, t, of a material is related to its t_(eq) for a givencapacitance, with SiO₂ having a dielectric constant κ_(ox)=3.9, ast=(κ/κ_(ox)) t_(eq)=(κ/3.9) t_(eq).

Thus, materials with a dielectric constant greater than that of SiO₂,3.9, will have a physical thickness that can be considerably larger thana desired t_(eq), while providing the desired equivalent oxidethickness. For example, an alternative dielectric material with adielectric constant of 10 could have a thickness of about 25.6 Å toprovide a t_(eq) of 10 Å, not including any depletion/inversion layereffects. Thus, a reduced equivalent oxide thickness for transistors canbe realized by using dielectric materials with higher dielectricconstants than SiO₂.

The thinner equivalent oxide thickness required for lower deviceoperating voltages and smaller device dimensions may be realized by asignificant number of materials, but additional fabricating requirementsmake determining a suitable replacement for SiO₂ difficult. The currentview for the microelectronics industry is still for silicon-baseddevices. This may require that the dielectric material employed be grownon a silicon substrate or a silicon layer, which places significantconstraints on the substitute dielectric material. During the formationof the dielectric on the silicon layer, there exists the possibilitythat a small layer of SiO₂ could be formed in addition to the desireddielectric. The result would effectively be a dielectric layerconsisting of two sublayers in parallel with each other and the siliconlayer on which the dielectric is formed. In such a case, the resultingcapacitance would be that of two dielectrics in series. As a result, thet_(eq) of the dielectric layer would be the sum of the SiO₂ thicknessand a multiplicative factor of the thickness, t, of the dielectric beingformed, written as t_(eq)=t_(SiO2)+(κ_(ox)/κ)t.

Thus, if a SiO₂ layer is formed in the process, the t_(eq) is againlimited by a SiO₂ layer. In the event that a barrier layer is formedbetween the silicon layer and the desired dielectric in which thebarrier layer prevents the formation of a SiO₂ layer, the t_(eq) wouldbe limited by the layer with the lowest dielectric constant. However,whether a single dielectric layer with a high dielectric constant or abarrier layer with a higher dielectric constant than SiO₂ is employed,the layer interfacing with the silicon layer should provide a highquality interface.

One of the advantages of using SiO₂ as a dielectric layer in a devicehas been that the formation of the SiO₂ layer results in an amorphousdielectric. Having an amorphous structure for a dielectric provides forreducing problems of leakage current associated with grain boundaries inpolycrystalline dielectrics that provide high leakage paths.

Additionally, grain size and orientation changes throughout apolycrystalline dielectric can cause variations in the film's dielectricconstant, along with uniformity and surface topography problems.Materials having a high dielectric constant relative to SiO₂ may alsohave a crystalline form, at least in a bulk configuration. The bestcandidates for replacing SiO₂ as a dielectric in a device are those thatcan be fabricated as a thin layer with an amorphous form and that havehigh dielectric constants.

Capacitor applications have used high-K dielectric materials, which areinsulating materials having a dielectric constant greater than silicondioxide. Such high-K dielectric materials include silicon oxynitride(SiON, κ˜6), alumina (Al₂O₃, κ˜9), and oxide/nitride composites(SiO₂/Si₃N₄, κ˜6). Other possible candidates include metal oxides(κ˜8-80), nitrides (κ˜7-30), oxynitrides (κ˜6-25), silicates (κ˜6-20),carbides (κ˜6-15), and complex titanates (κ˜>100). Factors for selectingappropriate materials include physical, chemical and thermal stabilityas well as etch-ability and stoichiometric reproducibility.

In field effect transistor (FET) applications, there are other factorsto consider while addressing device scalability. The selected dielectricshould provide stable amorphous and adherent films in the thicknessrange of 1 nm to 100 nm at temperatures ranging from room temperature to1000° C. A relatively defect-free composition that is uniform andreproducible with a fixed charge density and trap density of less than10¹¹ cm⁻² in films of such composition is a factor. A factor includesdielectric materials that provide a stable non-reactive interface with asilicon substrate such that the interface has an interface state densitymuch less than 10¹¹ cm². Such interface state densities may occur whensilicon bonds at the interface are saturated with high strength covalentbonds with molecular elements of the dielectric material. Another factordeals with current transport through the dielectric that should becontrolled by tunneling, which is independent of temperature, ratherthan by trap-assisted thermally dependent transport.

The conductivity of the dielectric should be equal to or lower than SiO₂films when voltage is stressed to a field strength of 5×10⁶ V/cm. Toaddress the current transport, a dielectric material having a bandgapgreater than 5 eV and having an electron and hole barrier height greaterthan 2 eV at a silicon interface may be considered. An additional factorto consider is using dielectric materials with a destructive breakdownstrength greater than 6×10⁶ V/cm. Other factors for selecting adielectric material for use in a variety of electronic devices, such asfor the dielectric in FETs, relates to processing characteristics. Suchprocessing characteristics include compatibility with gate material,selective etch-ability, chemical inertness to contaminants, dopant andpost processing environments (temperature, pressure, ambients), andintrinsic properties associated with annealing of defects/damages causedby post-processing such as ion-implantation, plasma-radiation, andgate/back-end processing.

In various embodiments, mixed metal oxynitrides (with silicon includedas a metal) are constructed as dielectric films in a variety ofelectronic devices and systems. Most oxynitrides are thermally stableand can integrate into semiconductor device processing. With nitrogenconcentration in an oxynitride film at 30% or higher, such oxynitridesare chemically inert. With processing conditions controlled to providevery low partial pressures of hydrogen and ON ions, oxynitride filmswith a wide range of nitrogen to oxygen ratio can be deposited over asilicon substrate with very low fixed charge and interface statesdensity. On the other hand, charge trapping and transportcharacteristics are dependent on relative ratio of nitrogen to oxygencontent in the constructed film. Films with nitrogen concentration twicethat of oxygen (for example, approximately 40 atomic percent nitrogen,approximately 20 atomic percent oxygen, and approximately 40 atomicpercent metal or silicon) have a lower bandgap, higher trap density, andtransport characteristics dominated by Frenkel-Poole conduction. Suchmaterials may not be well suited for gate dielectric applications.However, such films exhibit higher κ values. With increasing oxygenconcentration in oxynitride films, the bandgap is raised, currentleakage is reduced, and the low frequency κ value is also somewhatreduced. In addition with increasing oxygen concentration, the trapdensity is reduced, the trap energy depth is increased, and the carriertransport ceases to be trap-assisted, exhibits tunneling conduction, andhas a weak temperature dependence, if any. In various embodiments, adielectric layer includes an oxynitride film having approximately 30atomic % oxygen and approximately 30-35 atomic % nitrogen. With highenough nitrogen content, oxygen-vacancy induced defects in films isnegligible when compared with metal oxides.

Silicon oxynitride (SiON) has been used as a gate dielectric and gateinsulator for a non-volatile FET device. Silicon oxynitride at acomposition range of Si₂ON₂ exhibits a dielectric constant of 6.5 and abandgap of approximately 6.5 eV compared to a stoichiometric nitride ofK=7.5 and a bandgap of 5.1 eV. Aluminum oxynitride (AlON) is expected tohave a bandgap greater than 5 eV with a κ value similar to SiON.Compared to SiON, metal oxynitrides such as ZrON, HfON, LaON, and TaONand other single metal oxynitrides are expected to have a lower bandgap.

In various embodiments, bimetal (or metal/silicon) oxynitrides based onSi, Al, Hf, La, and Ta are used as dielectric films in a variety ofelectronic devices and systems. These bimetal oxynitrides may provide abandgap range from 5 eV to greater than 7 eV. Estimates for bandgapsinclude a bandgap of Si—Al—ON of greater than 7 eV, a bandgap ofSi—Hf—ON of about 6.9 eV, a bandgap of Al—Hf—ON of about 6.8 eV, abandgap of Si—Ta—ON of about 6 eV, a bandgap of Al—Ta—ON of about 6 eV.Bimetal oxynitrides Hf—Ta—ON, Hf—La—ON, Al—La—ON, Ta—La—ON, and Si—La—ONare estimated to exhibit significantly lower bandgaps. The κ value forSi—Al—ON is estimated at approximately 7 to 8, while the κ values forthe other oxynitrides of this group are estimated to be in the rangefrom about 15 to 25.

In an embodiment, a film of tantalum silicon oxynitride may be used as adielectric layer for application in a variety of electronic devices,replacing the use of silicon oxide to provide a higher dielectricconstant. The tantalum silicon oxynitride dielectric may be formed as atantalum silicon oxynitride film.

In various embodiments, a dielectric layer may be constructed containingtantalum silicon oxynitride formed using atomic layer deposition with ametal electrode formed in contact with the dielectric layer. The metalelectrode may be formed by atomic layer deposition. The metal electrodemay be formed by substituting a desired metal material for a previouslydisposed substitutable material. The metal electrode may be formed as aself aligned metal electrode on and contacting the dielectric layer. Themetal electrode may be formed on the dielectric layer using a previouslydisposed sacrificial carbon layer on the dielectric layer andsacrificial carbon sidewall spacers adjacent to the sacrificial carbonlayer.

The term tantalum silicon oxynitride is used herein with respect to acomposition that essentially consists of tantalum, silicon, oxygen, andnitrogen in a form that may be stoichiometric, non-stoichiometric, or acombination of stoichiometric and non-stoichiometric. A tantalum siliconoxynitride film may also be referred to as a tantalum silicon oxygennitrogen film. Other nomenclature for a composition that essentiallyconsists of silicon, tantalum, oxygen, and nitrogen may be known tothose skilled in the art. In an embodiment, tantalum silicon oxynitridemay be formed substantially as a stoichiometric tantalum siliconoxynitride film. In an embodiment, tantalum silicon oxynitride may beformed substantially as a non-stoichiometric tantalum silicon oxynitridefilm. In an embodiment, tantalum silicon oxynitride may be formedsubstantially as a combination film of non-stoichiometric tantalumsilicon oxynitride and stoichiometric tantalum silicon oxynitride.Herein, a tantalum silicon oxynitride composition may be expressed asTaSiON, TaSiON_(x), Ta_(x)Si_(y)O_(z)N_(r), or other equivalent form.Herein, a tantalum silicon oxynitride composition may be expressed asTaSiON, TaSiON_(r), Ta_(x)Si_(y)O_(z)N_(r), or other equivalent form.The expression TaSiON or its equivalent forms may be used to includeTaSiON in a form that is stoichiometric, non-stoichiometric, or acombination of stoichiometric and non-stoichiometric tantalum siliconoxynitride. The expressions TaO, TaO_(z), or its equivalent forms may beused to include tantalum oxide in a form that is stoichiometric,non-stoichiometric, or a combination of stoichiometric andnon-stoichiometric. The expressions SiO, SiO_(z), or its equivalentforms may be used to include silicon oxide in a form that isstoichiometric, non-stoichiometric, or a combination of stoichiometricand non-stoichiometric. With respect to forms that are stoichiometric,non-stoichiometric, or a combination of stoichiometric andnon-stoichiometric, expressions such as SiN, SiO, SiON, SiO_(z),SiN_(r), TaO_(t), TaN_(s), TaON_(r), TaON, etc. may be used in a similarmanner as SiO_(z). In various embodiments, a tantalum silicon oxynitridefilm may be doped with elements or compounds other than silicon,tantalum, oxygen, and nitrogen.

Atomic Layer Deposition

In an embodiment, a tantalum silicon oxynitride dielectric film may beformed using atomic layer deposition (ALD). Forming such structuresusing atomic layer deposition may allow control of transitions betweenmaterial layers. As a result of such control, atomic layer depositedtantalum silicon oxynitride dielectric films can have an engineeredtransition with a substrate surface. ALD, also known as atomic layerepitaxy (ALE), is a modification of chemical vapor deposition (CVD) andis also called “alternatively pulsed-CVD.” In ALD, gaseous precursorsare introduced one at a time to the substrate surface mounted within areaction chamber (or reactor). This introduction of the gaseousprecursors takes the form of pulses of each gaseous precursor. In apulse of a precursor gas, the precursor gas is made to flow into aspecific area or region for a short period of time. Between the pulses,the reaction chamber may be purged with a gas, where the purging gas maybe an inert gas. Between the pulses, the reaction chamber may beevacuated. Between the pulses, the reaction chamber may be purged with agas and evacuated.

In a chemisorption-saturated ALD (CS-ALD) process, during the firstpulsing phase, reaction with the substrate occurs with the precursorsaturatively chemisorbed at the substrate surface. Subsequent pulsingwith a purging gas removes precursor excess from the reaction chamber.

The second pulsing phase introduces another precursor on the substratewhere the growth reaction of the desired film takes place. Subsequent tothe film growth reaction, reaction byproducts and precursor excess arepurged from the reaction chamber. With favorable precursor chemistrywhere the precursors absorb and react with each other aggressively onthe substrate, one ALD cycle can be performed in less than one second inproperly designed flow type reaction chambers. Typically, precursorpulse times range from about 0.5 sec to about 2 to 3 seconds. Pulsetimes for purging gases may be significantly longer, for example, pulsetimes of about 5 to about 30 seconds.

In ALD, the saturation of all the reaction and purging phases makes thegrowth self-limiting. This self-limiting growth results in large areauniformity and conformality, which has important applications for suchcases as planar substrates, deep trenches, and in the processing ofporous silicon and high surface area silica and alumina powders. Atomiclayer deposition provides control of film thickness in a straightforwardmanner by controlling the number of growth cycles.

The precursors used in an ALD process may be gaseous, liquid or solid.However, liquid or solid precursors should be volatile. The vaporpressure should be high enough for effective mass transportation. Also,solid and some liquid precursors may need to be heated inside the atomiclayer deposition system and introduced through heated tubes to thesubstrates. The necessary vapor pressure should be reached at atemperature below the substrate temperature to avoid the condensation ofthe precursors on the substrate. Due to the self-limiting growthmechanisms of ALD, relatively low vapor pressure solid precursors can beused, though evaporation rates may vary somewhat during the processbecause of changes in their surface area.

There are several other characteristics for precursors used in ALD. Theprecursors should be thermally stable at the substrate temperature,because their decomposition may destroy the surface control andaccordingly the advantages of the ALD method that relies on the reactionof the precursor at the substrate surface. A slight decomposition, ifslow compared to the ALD growth, may be tolerated.

The precursors should chemisorb on or react with the surface, though theinteraction between the precursor and the surface as well as themechanism for the adsorption is different for different precursors. Themolecules at the substrate surface should react aggressively with thesecond precursor to form the desired solid film. Additionally,precursors should not react with the film to cause etching, andprecursors should not dissolve in the film. Using highly reactiveprecursors in ALD contrasts with the selection of precursors forconventional CVD.

The by-products in the reaction should be gaseous in order to allowtheir easy removal from the reaction chamber. Further, the by-productsshould not react or adsorb on the surface.

In a reaction sequence ALD (RS-ALD) process, the self-limiting processsequence involves sequential surface chemical reactions. RS-ALD relieson chemistry between a reactive surface and a reactive molecularprecursor. In an RS-ALD process, molecular precursors are pulsed intothe ALD reaction chamber separately. A metal precursor reaction at thesubstrate may be followed by an inert gas pulse to remove excessprecursor and by-products from the reaction chamber prior to pulsing thenext precursor of the fabrication sequence.

By RS-ALD, films can be layered in equal metered sequences that may allbe identical in chemical kinetics, deposition per cycle, composition,and thickness. RS-ALD sequences generally deposit less than a full layerper cycle. Typically, a deposition or growth rate of about 0.25 to about2.00 Å per RS-ALD cycle may be realized.

Processing by RS-ALD provides continuity at an interface avoiding poorlydefined nucleating regions that are typical for chemical vapordeposition (<20 Å) and physical vapor deposition (<50 Å), conformalityover a variety of substrate topologies due to its layer-by-layerdeposition technique, use of low temperature and mildly oxidizingprocesses, lack of dependence on the reaction chamber, growth thicknessdependent solely on the number of cycles performed, and ability toengineer multilayer laminate films with a resolution of one to twomonolayers. RS-ALD processes allow for deposition control on the orderof monolayers and the ability to deposit monolayers of amorphous films.

Herein, a sequence refers to the ALD material formation based on an ALDreaction of a precursor with its reactant precursor. For example,forming silicon nitride from a SiCl₄ precursor and NH₃, as its reactantprecursor, includes a silicon/nitrogen sequence. In various ALDprocesses that form a nitride or a composition that contains nitrogen, areactant precursor that contains nitrogen is used to supply nitrogen.Herein, a precursor that contains nitrogen and that supplies nitrogen tobe incorporated in the ALD composition formed, which may be used in anALD process with precursors supplying the other elements in the ALDcomposition, is referred to as a nitrogen reactant precursor. In theabove example, NH₃ is a nitrogen reactant precursor. Similarly, an ALDsequence for a metal oxide may be referenced with respect to the metaland oxygen. For example, an ALD sequence for silicon oxide may also bereferred to as a silicon/oxygen sequence. In various ALD processes thatform an oxide or a composition that contains oxygen, a reactantprecursor that contains oxygen is used to supply the oxygen. Herein, aprecursor that contains oxygen and that supplies oxygen to beincorporated in the ALD composition formed, which may be used in an ALDprocess with precursors supplying the other elements in the ALDcomposition, is referred to as an oxygen reactant precursor. With an ALDprocess using SiCl₄ and water vapor to form silicon oxide, water vaporis an oxygen reactant precursor. An ALD cycle may include pulsing aprecursor, pulsing a purging gas for the precursor, pulsing a reactantprecursor, and pulsing the reactant precursor's purging gas. An ALDcycle may include pulsing a precursor, evacuating the reactant chamber,pulsing a reactant precursor, and evacuating the reactant chamber. AnALD cycle may include pulsing a precursor, pulsing a purging gas for theprecursor and evacuating the reactant chamber, pulsing a reactantprecursor, and pulsing the reactant precursor's purging gas andevacuating the reactant chamber.

In forming a layer of a metal species, an ALD sequence may deal withpulsing a reactant precursor to the substrate surface on which ametal-containing species has been absorbed such that the reactantprecursor reacts with the metal-containing species resulting in thedeposited metal and a gaseous by-product that can be removed during thesubsequent purging/evacuating process. Alternatively, in forming a layerof a metal species, an ALD sequence may deal with reacting a precursorcontaining the metal species with a substrate surface. A cycle for sucha metal forming sequence may include pulsing a purging gas after pulsingthe precursor containing the metal species to deposit the metal.Additionally, deposition of a semiconductor material may be realized ina manner similar to forming a layer of a metal, given the appropriateprecursors for the semiconductor material.

In an ALD formation of a composition having more than two elements, acycle may include a number of sequences to provide the elements of thecomposition. For example, a cycle for an ALD formation of an ABO_(x)composition may include sequentially pulsing a first precursor/a purginggas for the first precursor/a first reactant precursor/the firstreactant precursor's purging gas/a second precursor/a purging gas forthe second precursor/a second reactant precursor/the second reactantprecursor's purging gas, which may be viewed as a cycle having twosequences. In an embodiment, a cycle may include a number of sequencesfor element A and a different number of sequences for element B. Theremay be cases in which ALD formation of an ABO_(x) composition uses oneprecursor that contains the elements A and B, such that pulsing the ABcontaining precursor followed by its reactant precursor onto a substratemay include a reaction that forms ABO_(x) on the substrate to provide anAB/oxygen sequence. A cycle of an AB/oxygen sequence may include pulsinga precursor containing A and B, pulsing a purging gas for the precursor,pulsing an oxygen reactant precursor to the A/B precursor, and pulsing apurging gas for the reactant precursor. A cycle may be repeated a numberof times to provide a desired thickness of the composition. In anembodiment, a cycle for an ALD formation of the quaternary composition,tantalum silicon oxygen nitrogen, may include sequentially pulsing afirst precursor/a purging gas for the first precursor/a first reactantprecursor/the first reactant precursor's purging gas/a secondprecursor/a purging gas for the second precursor/a second reactantprecursor/the second reactant precursor's purging gas/a thirdprecursor/a purging gas for the third precursor/a third reactantprecursor/the third reactant precursor's purging gas, which may beviewed as a cycle having three sequences. In an embodiment, a layersubstantially of a tantalum silicon oxynitride composition is formed ona substrate mounted in a reaction chamber using ALD in repetitivetantalum/oxygen and silicon/nitrogen sequences using precursor gasesindividually pulsed into the reaction chamber. In an embodiment, a layersubstantially of a tantalum silicon oxynitride composition is formed ona substrate mounted in a reaction chamber using ALD in repetitivesilicon/nitrogen and tantalum/oxygen sequences using precursor gasesindividually pulsed into the reaction chamber. In an embodiment, asubstantially tantalum silicon oxynitride composition is formed by ALDhaving approximately 30% nitrogen and 30% oxygen concentrations in theresultant TaSiON dielectric film.

FIG. 1 shows an embodiment of an atomic layer deposition system 100 forprocessing a dielectric film containing TaxSiyOzNr layer. The elementsdepicted are those elements necessary for discussion of variousembodiments for forming TaSiON such that those skilled in the art maypractice the present invention without undue experimentation. Asubstrate 110 is located inside a reaction chamber 120 of ALD system100. Also located within reaction chamber 120 is a heating element 130,which is thermally coupled to substrate 110 to control the substratetemperature. A gas-distribution fixture 140 introduces precursor gasesto the substrate 110. Each precursor gas originates from individual gassources 150-155 whose flow is controlled by mass-flow controllers156-161, respectively. Gas sources 150-155 provide a precursor gaseither by storing the precursor as a gas or by providing a location andapparatus for evaporating a solid or liquid material to form theselected precursor gas. Furthermore, additional gas sources may beincluded, one for each metal precursor employed and one for eachreactant precursor associated with each metal precursor.

Also included in the ALD system are purging gas sources 163, 164, eachof which is coupled to mass-flow controllers 166, 167, respectively.Furthermore, additional purging gas sources may be constructed in ALDsystem 100, one purging gas source for each precursor gas. For a processthat uses the same purging gas for multiple precursor gases, lesspurging gas sources are required for ALD system 100. Gas sources 150-155and purging gas sources 163-164 are coupled by their associatedmass-flow controllers to a common gas line or conduit 170, which iscoupled to the gas-distribution fixture 140 inside reaction chamber 120.Gas conduit 170 is also coupled to vacuum pump, or exhaust pump, 181 bymass-flow controller 186 to remove excess precursor gases, purginggases, and by-product gases at the end of a purging sequence from gasconduit 170.

Vacuum pump, or exhaust pump, 182 is coupled by mass-flow controller 187to remove excess precursor gases, purging gases, and by-product gases atthe end of a purging sequence from reaction chamber 120. Forconvenience, control displays, mounting apparatus, temperature sensingdevices, substrate maneuvering apparatus, and necessary electricalconnections as are known to those skilled in the art are not shown inFIG. 1. The use, construction and fundamental operation of reactionchambers for deposition of films are understood by those of ordinaryskill in the art of semiconductor fabrication. Embodiments of thepresent invention may be practiced on a variety of such reactionchambers without undue experimentation. Furthermore, one of ordinaryskill in the art will comprehend the necessary detection, measurement,and control techniques in the art of semiconductor fabrication uponreading the disclosure.

In an embodiment, a tantalum silicon oxynitride layer may be structuredas one or more monolayers. A film of tantalum silicon oxynitride,structured as one or more monolayers, may have a thickness that rangesfrom a monolayer to thousands of angstroms or more. The film may beprocessed using atomic layer deposition. Embodiments of an atomic layerdeposited tantalum silicon oxynitride layer have a larger dielectricconstant than silicon dioxide. Such dielectric layers provide asignificantly thinner equivalent oxide thickness compared with a siliconoxide layer having the same physical thickness. Alternatively, suchdielectric layers provide a significantly thicker physical thicknessthan a silicon oxide layer having the same equivalent oxide thickness.This increased physical thickness aids in reducing leakage current.

Prior to forming the tantalum silicon oxynitride film using ALD, thesurface on which the tantalum silicon oxynitride film is to be depositedmay undergo a preparation stage. The surface may be the surface of asubstrate for an integrated circuit. In an embodiment, the substrateused for forming a transistor may include a silicon or siliconcontaining material. In other embodiments, silicon germanium, germanium,gallium arsenide, silicon-on-sapphire substrates, or other suitablesubstrates may be used. A preparation process may include cleaning thesubstrate and forming layers and regions of the substrate, such asdrains and sources, prior to forming a gate dielectric in the formationof a metal oxide semiconductor (MOS) transistor. Alternatively, activeregions may be formed after forming the dielectric layer, depending onthe over-all fabrication process implemented. In an embodiment, thesubstrate is cleaned to provide an initial substrate depleted of itsnative oxide. In an embodiment, the initial substrate is cleaned also toprovide a hydrogen-terminated surface. In an embodiment, a siliconsubstrate undergoes a final hydrofluoric (HF) rinse prior to ALDprocessing to provide the silicon substrate with a hydrogen-terminatedsurface without a native silicon oxide layer.

Cleaning immediately preceding atomic layer deposition aids in reducingan occurrence of silicon oxide as an interface between a silicon-basedsubstrate and a tantalum silicon oxynitride dielectric formed using theatomic layer deposition process. The material composition of aninterface layer and its properties are typically dependent on processconditions and the condition of the substrate before forming thedielectric layer. Though the existence of an interface layer mayeffectively reduce the dielectric constant associated with thedielectric layer and its substrate interface layer, a SiO₂ interfacelayer or other composition interface layer may improve the interfacedensity, fixed charge density, and channel mobility of a device havingthis interface layer.

The sequencing of the formation of the regions of an electronic device,such as a transistor, being processed may follow typical sequencing thatis generally performed in the fabrication of such devices as is wellknown to those skilled in the art. Included in the processing prior toforming a dielectric may be the masking of substrate regions to beprotected during the dielectric formation, as is typically performed insemiconductor fabrication. In an embodiment, an unmasked region includesa body region of a transistor; however, one skilled in the art willrecognize that other semiconductor device structures may utilize thisprocess.

In various embodiments, between each pulsing of a precursor used in anatomic layer deposition process, a purging gas may be pulsed into theALD reaction chamber. Between each pulsing of a precursor, the ALDreactor chamber may be evacuated using vacuum techniques as is known bythose skilled in the art. Between each pulsing of a precursor, a purginggas may be pulsed into the ALD reaction chamber and the ALD reactorchamber may be evacuated.

In an embodiment, an ALD cycle for forming TaSiON includes sequencingcomponent-containing precursors in the order of tantalum, silicon, andnitrogen with appropriate purging between the differentcomponent-containing precursors. Full coverage or partial coverage of amonolayer on a substrate surface may be attained for pulsing of ametal-containing precursor. In an embodiment, an ALD cycle for formingTaSiON includes sequencing the component-containing precursors invarious permutations. In an embodiment, an ALD cycle to form tantalumsilicon oxynitride includes a number, x, of tantalum/oxygen sequencesand a number, y, of silicon/nitrogen sequences. In an embodiment, an ALDcycle to form tantalum silicon oxynitride includes a number, x, oftantalum/nitrogen sequences and a number, y, of silicon/oxygensequences. In an embodiment, the number of sequences x and y is selectedto engineer the relative amounts of tantalum, silicon, oxygen, andnitrogen. In an embodiment, the number of sequences x and y is selectedto form a nitrogen-rich tantalum silicon oxynitride. In an embodiment,the number of sequences x and y are selected to form an oxygen-richtantalum silicon oxynitride. The tantalum silicon oxynitride may beengineered as a tantalum-rich dielectric relative to the amount ofsilicon in the dielectric. The tantalum silicon oxynitride may beengineered as a silicon-rich dielectric relative to the amount oftantalum in the dielectric. The pulsing of the individualcomponent-containing precursors may be performed independently in anon-overlapping manner using the individual gas sources 150-155 and flowcontrollers 156-161 of ALD system 100 of FIG. 1.

Each precursor may be pulsed into the reaction chamber for apredetermined period, where the predetermined period can be setseparately for each precursor. Additionally, for various ALD formations,each precursor may be pulsed into the reaction chamber under separateenvironmental conditions. The substrate may be maintained at a selectedtemperature and the reaction chamber maintained at a selected pressureindependently for pulsing each precursor. Appropriate temperatures andpressures may be maintained, whether the precursor is a single precursoror a mixture of precursors.

A number of precursors containing a tantalum may be used to provide thetantalum to a substrate for an integrated circuit. In an embodiment, aprecursor containing tantalum may include Ta(OC₂H₃). In an embodiment, aprecursor containing tantalum may include TaCl₅. In an embodiment, atantalum-containing precursor is pulsed onto a substrate in an ALDreaction chamber.

In various embodiments, after pulsing the tantalum-containing precursorand purging the reaction chamber of excess precursor and by-productsfrom pulsing the precursor, a reactant precursor may be pulsed into thereaction chamber. The reactant precursor may be an oxygen reactantprecursor that may include, but is not limited to, one or more of water,atomic oxygen, molecular oxygen, ozone, hydrogen peroxide, awater-hydrogen peroxide mixture, alcohol, or nitrous oxide. In addition,the pulsing of the tantalum precursor may use a pulsing period thatprovides uniform coverage of a monolayer on the surface or may use apulsing period that provides partial coverage of a monolayer on thesurface during a tantalum sequence.

A number of precursors containing silicon may be used to provide thesilicon to a substrate for an integrated circuit. In an embodiment, asilicon halide, such as SiCl₄, may be used. Other silicon halides, suchas SiI₄, may be used. In an embodiment, NH₃ may be used as thenitrogen-containing precursor for a silicon/nitrogen sequence. Inaddition, the pulsing of the silicon precursor may use a pulsing periodthat provides uniform coverage of a monolayer on the surface or may usea pulsing period that provides partial coverage of a monolayer on thesurface during a silicon sequence.

In various embodiments, nitrogen may be used as a purging gas and acarrier gas for one or more of the sequences used in the ALD formationof tantalum silicon oxynitride. Alternatively, hydrogen, argon gas, orother inert gases may be used as the purging gas. Excess precursor gasand reaction by-products may be removed by the purge gas. Excessprecursor gas and reaction by-products may be removed by evacuation ofthe reaction chamber using various vacuum techniques. Excess precursorgas and reaction by-products may be removed by the purge gas and byevacuation of the reaction chamber.

In an embodiment, after repeating a selected number of ALD cycles, adetermination is made as to whether the number of cycles equals apredetermined number to form the desired tantalum silicon oxynitridelayer. If the total number of cycles to form the desired thickness hasnot been completed, a number of cycles is repeated. In an embodiment,the thickness of a tantalum silicon oxynitride layer formed by atomiclayer deposition is determined by a fixed growth rate for the pulsingperiods and precursors used, set at a value such as N nm/cycle, and thenumber of cycles conducted. In an embodiment, depending on theprecursors used for ALD formation of a TaSiON film, the process isconducted in an ALD window, which is a range of temperatures in whichthe growth rate is substantially constant. In an embodiment, if such anALD window is not available, the ALD process is conducted at the sameset of temperatures for each ALD sequence in the process. For a desiredtantalum silicon oxynitride layer thickness, t, in an application, theALD process is repeated for t/N total cycles. Once the t/N cycles havecompleted, no further ALD processing for the tantalum silicon oxynitridelayer is required. In an embodiment, a tantalum silicon oxynitride layerprocessed at relatively low temperatures associated with atomic layerdeposition provides an amorphous layer.

In an embodiment, a TaSiON film may be grown to a desired thickness byrepetition of a process including atomic layer deposition of layers ofTaO and SiN and/or layers of SiO and TaN followed by annealing. In anembodiment, a base thickness may be formed according to variousembodiments such that forming a predetermined thickness of a TaSiON filmmay be conducted by forming a number of layers having the basethickness. As can be understood by one skilled in the art, determiningthe base thickness depends on the application and can be determinedduring initial processing without undue experimentation. Relativeamounts of tantalum, silicon, oxygen, and nitrogen in a TaSiON film maybe controlled by regulating the relative thicknesses of the individuallayers of oxides and nitrides formed. In addition, relative amounts oftantalum, silicon, oxygen, and nitrogen in a TaSiON film may becontrolled by forming a layer of TaSiON as multiple layers of differentbase thickness and by regulating the relative thicknesses of theindividual layers of oxides and nitrides formed in each base layer priorto annealing. As can be understood by those skilled in the art,particular effective growth rates for the engineered tantalum siliconoxynitride film can be determined during normal initial testing of theALD system used in processing a tantalum silicon oxynitride dielectricfor a given application without undue experimentation.

Atomic Layer Deposition and Nitridization

FIG. 2A shows a flow diagram of features of an embodiment for formingTaSiON using atomic layer deposition and nitridization. At 210, a layerof TaSiO is formed using atomic layer deposition. At 220, the layer ofTaSiO is subjected to a nitridization to form a TaSiON film. Thenitridization may be a high temperature nitridization. In thenitridization process, active nitrogen may be introduced by microwaveplasma. In the nitridization process, active nitrogen may be introducedby a NH₃ anneal. A high temperature nitridization is a nitridizingprocess that is performed at temperatures equal to or above 500° C. Invarious embodiments, TaSiO may be formed by atomic layer depositionusing ALD cycles of tantalum/oxygen sequences and silicon/oxygensequences. Depending on the amounts of tantalum, silicon, and oxygen tobe provided in the TaSiO film, the ALD cycle can be selected from anumber of different permutations of tantalum/oxygen sequences andsilicon/oxygen sequences.

FIG. 2B shows a flow diagram of features of an embodiment for formingTaSiO using atomic layer deposition for nitridization to a TaSiON film.At 230, a layer of tantalum oxide is formed on a substrate by atomiclayer deposition. At 240, a layer of silicon oxide is formed by atomiclayer deposition on the layer of tantalum oxide. At 250, the layers oftantalum oxide and silicon oxide are annealed to form a layer of TaSiO.In an embodiment, forming a tantalum oxide by atomic layer deposition isconducted after an initial tantalum oxide layer is formed on asilicon-based substrate to limit the size or occurrence of a siliconoxide interface between the TaSiO layer and a silicon-based substrate.The layer of TaSiO may be nitridized to form TaSiON. Alternatively, thelayers of tantalum oxide and silicon oxide may be nitridized during theannealing process. In an embodiment, alternating layers of ALD tantalumoxide and ALD silicon oxide may be formed to a desired thickness priorto nitridization. In an embodiment, a layer of ALD tantalum oxide and alayer of ALD silicon oxide may be formed, each to a desired thickness,the layers of ALD tantalum oxide and ALD silicon oxide nitridized toform a TaSiON layer. Then, a layer of ALD tantalum oxide and a layer ofALD silicon oxide may be formed on the TaSiON layer, the layers of ALDtantalum oxide and ALD silicon oxide nitridized to form a TaSiON layeron and contiguous with the previously formed TaSiON layer. This processmay be continued until the desired thickness of TaSiON is formed.

In an embodiment, ALD TaO may be formed using a number of precursorscontaining tantalum to provide the tantalum to a substrate for anintegrated circuit. Such tantalum containing precursors include, but arenot limited to, Ta(0C₂H₅)₅ and TaCl₅. In an embodiment, the tantalumoxide layer is Ta₂O₅. In an embodiment, Ta2O₅ layer is be formed at 250°C.-325° C.

After pulsing the tantalum-containing precursor and purging the reactionchamber of excess precursor and by-products from pulsing the precursor,an oxygen reactant precursor may be pulsed into the reaction chamber.The oxygen reactant precursor may include, but is not limited to, one ormore of water, atomic oxygen, molecular oxygen, ozone, hydrogenperoxide, a water-hydrogen peroxide mixture, alcohol, or nitrous oxide.After pulsing the oxygen-containing precursor the reaction chamber maybe purged of excess precursor and by-products. In addition, the pulsingof the precursors may use pulsing periods that provide uniform coverageof a monolayer on the surface or may use pulsing periods that providepartial coverage of a monolayer on the surface during a tantalum/oxygenALD cycle.

In an embodiment, ALD SiO may be formed using a number of precursorscontaining silicon to provide the silicon to a substrate for anintegrated circuit. Such silicon-containing precursors include, but arenot limited to, a silicon halide, such as SiCl₄. Other silicon halides,such as SiI₄, may be used. After pulsing the silicon-containingprecursor and purging the reaction chamber of excess precursor andby-products from pulsing the precursor, an oxygen reactant precursor maybe pulsed into the reaction chamber. The oxygen reactant precursor mayinclude, but is not limited to, one or more of water, atomic oxygen,molecular oxygen, ozone, hydrogen peroxide, a water-hydrogen peroxidemixture, alcohol, or nitrous oxide. In addition, the pulsing of theprecursors may use pulsing periods that provide uniform coverage of amonolayer on the surface or may use pulsing periods that provide partialcoverage of a monolayer on the surface during an ALD cycle forming SiO.

In various embodiments, nitrogen may be used as a purging gas and acarrier gas for one or more of the sequences. Alternatively, hydrogen,argon gas, or other inert gases may be used as the purging gas. Excessprecursor gas and reaction by-products may be removed by the purge gas.Excess precursor gas and reaction by-products may be removed byevacuation of the reaction chamber using various vacuum techniques.Excess precursor gas and reaction by-products may be removed by thepurge gas and by evacuation of the reaction chamber.

Atomic Layer Deposition and Oxidation

FIG. 3 shows a flow diagram of features of an embodiment for formingTaSiON using atomic layer deposition and oxidation. At 310, a layer ofTaN is formed by atomic layer deposition. At 320, a layer of SiN isformed by atomic layer deposition on the layer of TaN. SiN and TaN filmsmay be alternately deposited in adjacent layers, in which either nitridelayer may be deposited as the starting layer. At 330, the layers of TaNand SiN are annealed. At 340, the annealed layers of TaN and SiN areoxidized to form TaSiON. In an embodiment, the annealing and oxidationmay be performed together. The layers of TaN and SiN may be annealed andoxidized by rapid thermal oxidation to form TaSiON.

In an embodiment, ALD SiN may be formed using a number of precursorscontaining silicon to provide the silicon to a substrate for anintegrated circuit. Such silicon-containing precursors include, but arenot limited to, a silicon halide, such as SiCl₄. Other silicon halides,such as SiI₄, may be used. In an embodiment, during the pulsing of aSiCl₄ precursor, the substrate may be maintained at a temperatureranging from about 340° C. to about 375° C. In an embodiment, thesubstrate may be maintained at a temperature less than 550° C. In anembodiment, NH₃ may be used as the nitrogen-containing precursor for asilicon/nitrogen sequence. An NH₃ precursor may be pulsed at atemperature of 550° C. In various embodiments, use of the individualsilicon-containing precursors is not limited to the temperature rangesof the above example embodiments. Further, forming silicon nitride byatomic layer deposition is not limited to the abovementioned precursors.In addition, the pulsing of the silicon precursor may use a pulsingperiod that provides uniform coverage of a monolayer on the surface ormay use a pulsing period that provides partial coverage of a monolayeron the surface during a silicon/nitrogen sequence.

In an embodiment, ALD TaN may be formed using a number of precursorscontaining tantalum to provide the tantalum to a substrate for anintegrated circuit. Such tantalum containing precursors include, but arenot limited to, Ta(OC₂H₅)₅ and TaCl₅.

In an embodiment, H₂ may be pulsed along with the tantalum precursor orthe precursor to reduce carbon contamination in the deposited film.After pulsing the tantalum-containing precursor and purging the reactionchamber of excess precursor and by-products from pulsing the precursor,a reactant precursor may be pulsed into the reaction chamber. To formTaN, a nitrogen reactant precursor is pulsed. A number of precursorscontaining nitrogen may be used to provide nitrogen. Suchnitrogen-containing precursors include, but are not limited to,nitrogen, ammonia (NH₃), tert-butylamine (C₄H₁₁N), allylamine (C₃H₇N),and 1,1-dimethylhydrazine ((CH₃)₂NNH₂). In an embodiment, the substrateis maintained at a temperature ranging from about 400° C. to about 500°C. using tert-butylamine or allylamine as a nitrogen precursor. In anembodiment, NH₃ may be pulsed with the tert-butylamine and theallylamine. The addition of NH₃ may enhance the deposition rate at lowertemperatures. In various embodiments, use of the individualtantalum-containing precursors is not limited to the temperature rangesof the above example embodiments. Further, forming tantalum nitride byatomic layer deposition is not limited to the abovementioned precursors.In addition, the pulsing of the tantalum precursor may use a pulsingperiod that provides uniform coverage of a monolayer on the surface ormay use a pulsing period that provides partial coverage of a monolayeron the surface during a tantalum/nitrogen sequence.

In various embodiments, nitrogen may be used as a purging gas and acarrier gas for one or more of the sequences. Alternatively, hydrogen,argon gas, or other inert gases may be used as the purging gas. Excessprecursor gas and reaction by-products may be removed by the purge gas.Excess precursor gas and reaction by-products may be removed byevacuation of the reaction chamber using various vacuum techniques.Excess precursor gas and reaction by-products may be removed by thepurge gas and by evacuation of the reaction chamber.

Atomic Layer Deposition and Annealing

FIG. 4 shows a flow diagram of features of an embodiment for formingTaSiON using atomic layer deposition and annealing. At 410, a layer ofTaON is formed using atomic layer deposition. At 420, a layer of SiO isformed using atomic layer deposition on the layer of TaON. At 430, alayer of SiN is formed using atomic layer deposition on the layer ofSiO. At 440, the layers of TaON, SiO, and SiN are annealed to form alayer of TaSiON. TaON, SiO, and SiN films may be alternately depositedin adjacent layers, in which any of the layers may be deposited as thestarting layer. In an embodiment, forming a silicon oxide or siliconnitride using atomic layer deposition is conducted after an initialtantalum oxynitride layer is formed on a silicon-based substrate tolimit the size or occurrence of a silicon oxygen interface between aTaSiON layer and the substrate.

In an embodiment, ALD SiO may be formed using a number of precursorscontaining silicon to provide the silicon to a substrate for anintegrated circuit. Such silicon-containing precursors include, but arenot limited to, a silicon halide, such as SiCl₄. Other silicon halides,such as SiL₄, may be used. After pulsing the silicon-containingprecursor and purging the reaction chamber of excess precursor andby-products from pulsing the precursor, an oxygen reactant precursor maybe pulsed into the reaction chamber. The oxygen reactant precursor mayinclude, but is not limited to, one or more of water, atomic oxygen,molecular oxygen, ozone, hydrogen peroxide, a water-hydrogen peroxidemixture, alcohol, or nitrous oxide. In addition, the pulsing of theprecursors may use pulsing periods that provide uniform coverage of amonolayer on the surface or may use pulsing periods that provide partialcoverage of a monolayer on the surface during an ALD cycle forming SiO.

In various embodiments, nitrogen may be used as a purging gas and acarrier gas for one or more of the sequences. Alternatively, hydrogen,argon gas, or other inert gases may be used as the purging gas. Excessprecursor gas and reaction by-products may be removed by the purge gas.Excess precursor gas and reaction by-products may be removed byevacuation of the reaction chamber using various vacuum techniques.Excess precursor gas and reaction by-products may be removed by thepurge gas and by evacuation of the reaction chamber.

In an embodiment, ALD SiN may be formed using a number of precursorscontaining silicon to provide the silicon to a substrate for anintegrated circuit. Such silicon-containing precursors include, but arenot limited to, a silicon halide, such as SiCl₄. Other silicon halides,such as SiL₄, may be used. In an embodiment, during the pulsing of aSiCl₄ precursor, the substrate may be maintained at a temperatureranging from about 340° C. to about 375° C. In an embodiment, thesubstrate may be maintained at a temperature less than 550° C. In anembodiment, NH₃ may be used as the nitrogen-containing precursor for asilicon/nitrogen sequence. An NH₃ precursor may be pulsed at atemperature of 550° C. In various embodiments, use of the individualsilicon-containing precursors is not limited to the temperature rangesof the above example embodiments. Further, forming silicon nitride byatomic layer deposition is not limited to the abovementioned precursors.In addition, the pulsing of the silicon precursor may use a pulsingperiod that provides uniform coverage of a monolayer on the surface ormay use a pulsing period that provides partial coverage of a monolayeron the surface during a silicon/nitrogen sequence.

In various embodiments, nitrogen may be used as a purging gas and acarrier gas for one or more of the sequences. Alternatively, hydrogen,argon gas, or other inert gases may be used as the purging gas. Excessprecursor gas and reaction by-products may be removed by the purge gas.Excess precursor gas and reaction by-products may be removed byevacuation of the reaction chamber using various vacuum techniques.Excess precursor gas and reaction by-products may be removed by thepurge gas and by evacuation of the reaction chamber.

In an embodiment, ALD TaON may be formed using a number of precursorscontaining tantalum to provide the tantalum to form a tantalum layer.Such tantalum containing precursors include, but are not limited to,Ta(OC₂H₅)₅ and TaCl₅.

After pulsing the tantalum-containing precursor and purging the reactionchamber of excess precursor and by-products from pulsing the precursor,a reactant precursor may be pulsed into the reaction chamber. A nitrogenreactant precursor may be pulsed. A number of precursors containingnitrogen may be used to provide nitrogen. Such nitrogen-containingprecursors include, but are not limited to, nitrogen, ammonia (NH₃),tert-butylamine (C₄H₁₁N), allylamine (C₃H₇N), and 1,1-dimethylhydrazine((CH₃)₂NNH₂).

After pulsing the nitrogen-containing precursor and purging the reactionchamber of excess precursor and by-products from pulsing the precursor,an oxygen reactant precursor may be pulsed into the reaction chamber.The oxygen reactant precursor may include, but is not limited to, one ormore of water, atomic oxygen, molecular oxygen, ozone, hydrogenperoxide, a water-hydrogen peroxide mixture, alcohol, or nitrous oxide.In various embodiments, the order of pulsing the precursors may vary. Invarious embodiments, forming tantalum oxynitride by atomic layerdeposition is not limited to the abovementioned precursors. In addition,the pulsing of the precursors may use pulsing periods that provideuniform coverage of a monolayer on the surface or may use pulsingperiods that provide partial coverage of a monolayer on the surfaceduring an ALD cycle forming TaON.

Dielectric Structures

In various embodiments, either before or after forming a TaSiON film,other dielectric layers such as SiO, TaO, SiN, SiON, TaON, TaNdielectric nitride layers, dielectric metal silicates, insulating metaloxides, or combinations thereof are formed as part of a dielectric layeror dielectric stack. In an embodiment, these one or more other layers ofdielectric material may be provided in stoichiometric form, innon-stoichiometric form, or a combination of stoichiometric dielectricmaterial and non-stoichiometric dielectric material. In an embodiment,depending on the application, a dielectric stack containing a TaSiON_(x)film includes a silicon oxide layer. In an embodiment, the dielectriclayer is formed as a nanolaminate. An embodiment of a nanolaminateincludes a layer of a silicon oxide and a TaSiON_(x) film, a layer ofsilicon nitride and a TaSiON_(x) film, a layer of tantalum oxide and aTaSiON_(x) film, a layer of silicon oxynitride and a TSiON_(x) film, alayer of tantalum oxynitride and a TaSiON_(x) film, layers of siliconoxide, tantalum oxide, silicon nitride, silicon oxynitride, and tantalumoxynitride along with a TaSiON_(x) film, or various other combinations.In an embodiment, a dielectric layer is formed substantially as thetantalum silicon oxynitride film.

In various embodiments, the structure of an interface between adielectric layer and a substrate on which it is disposed is controlledto limit the inclusion of silicon oxide, since a silicon oxide layerwould reduce the effective dielectric constant of the dielectric layer.In an embodiment, the material composition and properties for aninterface layer are dependent on process conditions and the condition ofthe substrate before forming the dielectric layer. In an embodiment,though the existence of an interface layer may effectively reduce thedielectric constant associated with the dielectric layer and itssubstrate, the interface layer, such as a silicon oxide interface layeror other composition interface layer, may improve the interface density,fixed charge density, and channel mobility of a device having thisinterface layer.

In an embodiment, a tantalum silicon oxynitride layer is doped withother elements. The doping may be employed to enhance the leakagecurrent characteristics of the dielectric layer containing theTaSiON_(x) film by providing a disruption or perturbation of thetantalum silicon oxynitride structure. In an embodiment, such doping isrealized by substituting a sequence of one of these elements for asilicon sequence, a tantalum sequence, or various combinations ofsequences. The choice for substitution may depend on the form of thetantalum silicon oxynitride structure with respect to the relativeamounts of silicon atoms and tantalum atoms desired in the oxide. In anembodiment, to maintain a substantially tantalum silicon oxynitride, theamount of dopants inserted into the oxynitride are limited to arelatively small fraction of the total number of silicon and tantalumatoms.

After forming a dielectric having a tantalum silicon oxynitride layer,other material may be formed upon the tantalum silicon oxynitride layer.In an embodiment, the other material is a conductive material. Theconductive material may be used as an electrode. Such electrodes may beused as capacitor electrodes, control gates in transistors, or floatinggates in floating gate transistors. In an embodiment, the conductivematerial is a metal or conductive metal nitride. In an embodiment, theconductive material is a conductive semiconductor material. In anembodiment, the conductive material is formed by ALD processes. In anembodiment, the conductive material is formed by a substitution process.In an embodiment, the conductive material is formed in a self-alignmentprocess.

Atomic Layer Deposition of Conductive Layers

In various embodiments, a conductive layer may be deposited by atomiclayer deposition on a layer of TaSiON or on a dielectric layercontaining a layer of TaSiON. A metal layer may be deposited by atomiclayer deposition in an ALD cycle having a halide precursor containingthe metal to be deposited and a reactant precursor containing hydrogen.Metal layer formation by ALD is not limited to halide precursors andhydrogen reactant precursors. In various embodiments, precursors may beselected to form ALD conductive layers such as aluminum (Al), tungsten(W), molybdenum (Mo), gold (Au), silver (Ag), gold alloy, silver alloy,copper (Cu), platinum (Pt), rhenium (Re), ruthenium (Ru), rhodium (Rh),nickel (Ni), osmium (Os), palladium (Pd), iridium (Ir), cobalt (Co),germanium (Ge), or metallic nitrides such as WN, TiN or TaN. Formationof ALD conductive layers is not limited to the abovementioned materials.

In an example embodiment, a tantalum layer may be formed on a TaSiONfilm by atomic layer deposition using a tantalum-containing precursor.In an embodiment, a tantalum halide precursor, such as TaF₅ or TaCl₅,may be used with hydrogen as a reactant precursor. In an embodiment, aTaCl₅ precursor may be used with an atomic hydrogen reactant precursor.The atomic hydrogen reactant precursor may be provided using a plasma.In an embodiment, the substrate temperature may be held at a temperatureranging from about 250° C. to about 400° C. The hydrogen reactantprecursor reacts at the substrate to remove the halogen, which forms theselected tantalum halide precursor, leaving tantalum on the substratesurface. After pulsing a tantalum-containing precursor and after pulsingits reactant precursor, the reaction chamber may be purged of excessprecursor and/or by-products. In various embodiments, use of theindividual tantalum-containing precursors is not limited to thetemperature ranges of the above example embodiments. Further, formingtantalum by atomic layer deposition is not limited to the abovementionedprecursors. In addition, the pulsing of the tantalum precursor may use apulsing period that provides uniform coverage of a monolayer on thesurface or may use a pulsing period that provides partial coverage of amonolayer on the surface. The tantalum layer may be structured as one ormore monolayers. The tantalum layer may have a thickness ranging from amonolayer to thousands of angstroms or more.

In an example embodiment, a metal nitride layer may be deposited byatomic layer deposition using a precursor containing the metal to bedeposited and a reactant precursor containing nitrogen in an ALD cycle.In an example embodiment, a titanium nitride layer may be formed with aTaSiON film by atomic layer deposition using a titanium-containingprecursor. A nitrogen-containing precursor may be used as the reactantprecursor for the titanium-containing precursor. The titanium-containingprecursor and the nitrogen-containing precursor may be selected suchthat their use does not form a titanium oxide in the layer of titaniumnitride being formed. The titanium-containing precursor and thenitrogen-containing precursor may be selected such that these precursorsdo not include oxygen as an elemental component. In an embodiment, atitanium halide precursor, such as TiCl₄, TiI₄, or TiF₄, may be usedwith NH₃ as a reactant precursor. In an embodiment, a TiCl₄ precursormay be used with a NH₃ reactant precursor. In an embodiment, thesubstrate temperature may be held at a temperature ranging from about380° C. to about 500° C. In an embodiment, the substrate temperature maybe held at a temperature less than 600° C. After pulsing atitanium-containing precursor and after pulsing its reactant precursor,the reaction chamber may be purged of excess precursor and/orby-products. In various embodiments, use of the individualtitanium-containing precursors is not limited to the temperature rangesof the above example embodiments. Further, forming titanium nitride byatomic layer deposition is not limited to the abovementioned precursors,but may include precursors containing oxygen. In addition, the pulsingof the titanium precursor may use a pulsing period that provides uniformcoverage of a monolayer on the surface or may use a pulsing period thatprovides partial coverage of a monolayer on the surface. The titaniumnitride layer may be structured as one or more monolayers. The titaniumnitride layer may have a thickness ranging from a monolayer to thousandsof angstroms or more.

Metal Substitution

FIGS. 5A-5E illustrate an embodiment of a process for forming a metalsubstituted electrode in place of a previously deposited material on adielectric containing TaSiON. Though a transistor is discussed withreference to FIGS. 5A-5E, such a process may be used with respect toother embodiments of device configurations. FIG. 5A shows a substrate501 and shallow trench isolation (STI) regions 502. The substrate 501can be a semiconductor wafer as well as structures having one or moreinsulative, semi-insulative, conductive, or semiconductive layers andmaterials. Thus, for example, the substrate can includesilicon-on-insulator, silicon-on-sapphire, and other structures uponwhich semiconductor devices are formed.

FIG. 5B further shows a gate dielectric layer 503 formed on thesubstrate 501, and a gate substitutable layer 504 formed on the gatedielectric layer 503. The gate dielectric layer may include a dielectriclayer containing TaSiON in addition to other insulative material or adielectric layer essentially of TaSiON. The use of such a high-κdielectric increases the capacitance, which is useful for nanoscaleintegrated circuits. In various embodiments the gate dielectric includesstacked layers comprising one or more high-κ dielectric materials. Asdescribed in more detail below, the material of the gate substitutablelayer 504 is selected with respect to the desired gate material to allowthe gate material to replace the gate substitutable layer. This processforms a gate of the desired gate metal where the substitutable materialwas positioned on the gate dielectric.

As shown in FIG. 5C, portions of the gate dielectric layer 503 and thegate substitutable layer 504 are removed to define a gate 505. Sidewallsor spacers 506 are formed along the gate 505. Source/drain regions 507are also formed. Source/drain regions 507 can be formed usingconventional ion implantation and subsequent annealing. These annealingtemperatures can pose problems for aluminum gates and other metal gatesthat have melting temperatures less than the anneal temperature for thesource/drain regions.

FIG. 5D shows an insulative fill layer 508 provided to match thethickness of the gate stack. A planarization procedure, such aschemical-mechanical polishing, can be used to provide an even surfaceacross the fill layer 508 and the gate substitutable layer 504. A metallayer 509, formed of material intended to be the gate material, isdeposited over the gate substitutable layer 504 and the fill layer 508.The metal layer 509 is also referred to herein as a layer of gatematerial. Various deposition processes, such as evaporation, sputtering,chemical vapor deposition, or atomic layer deposition, may be used toform the metal layer 509. The volume of layer 509 is significantlylarger than the volume of the substitutable material left on the wafer.

After the metal layer 509 is deposited on the gate substitutable layer,a metal-substitution reaction is induced. The reaction can be providedby annealing the structure in a non-oxidizing atmosphere such as anitrogen gas or a forming gas. The heating urges diffusion ordissolution of the intended gate material in metal layer 509 for thesubstitutable material 504. The substitution process is bounded by thespacers 506 and the gate dielectric 503.

At the conclusion of the substitution reaction, the residual metal oflayer 509 and the substitutable material may be removed such as may beachieved using conventional planarization. FIG. 5E shows the resultinglow-resistance gate structure. The illustrated structure includes ametal substituted gate 510 formed by the substitution of the metal oflayer 509. The metal substituted gate 510 may include a small amount ofthe gate substitutable material that did not diffuse above theplanarization level 511. Such small amounts of the gate substitutablematerial do not significantly affect the conductivity of the metalsubstituted gate 510, and thus do not significantly affect theperformance of the device.

Drain and source contacts (not shown) can be formed, as well asinterconnects to other transistors or components, using conventionaltechniques. Another heat treatment may occur after packaging theintegrated circuit in a protective housing in an attempt to minimize theresistivity of the metal gate contacts and other metal interconnections.

The metal gate substitution technique, as disclosed herein, can beapplied to MOS devices, as generally illustrated in FIG. 5E, as well asto form metal floating gates and/or metal control gates in nonvolatiledevices. Additionally, various high-κ dielectrics having a TaSiON filmcan be used between the floating gate and the substrate, and between thecontrol gate and the floating gate in these nonvolatile devices.

FIG. 6 illustrates a flow diagram of features of an embodiment of ametal substitution technique. At 612, a gate dielectric is formed on asubstrate. The gate dielectric includes a TaSiON film. At 613, a layerof gate substitutable material is formed on the gate dielectric.Examples of gate substitutable material include polysilicon, germanium,silicon-germanium, and carbon. At 614, source/drain regions are formed.A layer of gate material is formed at 615 on the gate substitutablematerial. Examples of such metals include gold, silver, and aluminum.Other metals may be used. At 616, the gate material is substituted forthe layer of gate substitutable material.

A metal substitution reaction substitutes or replaces the substitutablematerial (e.g. silicon, germanium, silicon-germanium, carbon) with ametal. After the substitution, the resulting gate structure includessubstantially all of the desired metal. Small amounts of thesubstitutable material may remain in the gate structure. Thesubstitution reaction can be induced by heating the integrated circuitassembly to a desired temperature in a vacuum, nitrogen, argon, forminggas or other non-oxidizing atmosphere. Heating causes diffusion of themetal layer 509 into the substitutable layer. The annealing temperaturefor the substitution is less than the eutectic (lowest melting)temperature of materials involved in the substitution for the reactionfor substitution to occur. In an embodiment, to form a gold gate, ametal layer may be formed from gold and annealed at approximately 300°C. to substitute the gold for a silicon substitutable structure. In anembodiment, to form a silver gate, a metal layer may be formed fromsilver and annealed at approximately 500-600° C. to substitute thesilver for a silicon substitutable structure. A polysilicon andgermanium substitutable material may be used, which reduces the annealtemperature.

According to various embodiments, the gate substitutable material 504shown in FIGS. 5A-5E includes polysilicon. In some embodiments, the gatesubstitutable material includes germanium. Some embodiments usesilicon-germanium with a percentage of silicon in the range from 0% to100% as the gate substitutable material 504. Some embodiments use carbonas the gate substitutable material 504. With respect to variousembodiments which use polysilicon, germanium, or silicon-germanium asthe gate substitutable material 504, a replacement metal for thesubstituted gate may include aluminium, silver, gold, an alloy ofsilver, an alloy of gold as the replacement metal, or combinationsthereof. In various embodiments, with carbon used as the gatesubstitutable material 504, a replacement metal for the substituted gatemay include gold, silver, an alloy of gold, an alloy of silver, copper,platinum, rhenium, ruthenium, rhodium, nickel, osmium, palladium,iridium, cobalt, germanium, or combinations thereof.

Various embodiments form an integrated circuit structure using two ormore substitution reactions. Relatively higher temperature substitutionprocesses can be performed before relatively lower temperaturesubstitution processes. One application for multiple substitutionreactions is to independently adjust work functions of NMOS and PMOStransistors in CMOS integrated circuits. Multiple substitution reactionsare not limited to this CMOS integrated circuit application. Additionalinformation regarding metal substitution can be found in U.S. patentapplication Ser. No. 11/176,738 filed Jul. 7, 2005, entitled“METAL-SUBSTITUTED TRANSISTOR GATES,” which is herein incorporated byreference.

Self Aligned Metal Technique

FIGS. 7A-7D illustrate an embodiment of a process for forming a selfaligned conductive layer such as a metal gate for a transistorstructure. FIG. 7A illustrates a high-κ gate dielectric 710 containingTaSiON formed on a substrate 701. The substrate 701 can be asemiconductor wafer as well as structures having one or more insulative,semi-insulative, conductive, or semiconductive layers and materials.Thus, for example, the substrate can include silicon-on-insulator,silicon-on-sapphire, and other structures upon which semiconductordevices are formed.

In FIG. 7A, a sacrificial gate 703 is formed of amorphous carbon on thehigh-κ gate dielectric 710. In various embodiments, an etch barrier 708is formed over the sacrificial gate and the dielectric. The etch barrier708 includes silicon nitride or aluminum oxide, and can be formed usinga deposition process, according to various embodiments. Sacrificialsidewall spacers 706 are added adjacent the sacrificial gate 703. Invarious embodiments, the spacers 706 are formed of amorphous carbon bydeposition and conventional direct etch techniques. An ion implantation730 and high temperature anneal are used to form source/drain regions702 in areas defined by the sacrificial sidewall spacers 706. Theseannealing temperatures can pose problems for aluminum gates and othermetal gates that have melting temperatures less than the annealtemperature for the source/drain regions.

In FIG. 7B, the sacrificial sidewall spacers (706 in FIG. 7A) have beenremoved. Various embodiments use a plasma oxidation process to removethe sacrificial sidewall spacers. In addition, the etch barrier (708 inFIG. 7A) has been removed. In various embodiments, a light dose ionimplantation 740 is used to form source/drain extensions 742 in thesubstrate 701. The extensions 742 can be annealed at lower temperaturesand in shorter times than the more heavily doped source/drain regions702. According to various embodiments, source/drain extensions for thetransistor may be formed with doping the substrate to a depth of 30 nmor less.

In FIG. 7C, conventional or non-carbon sidewall spacers 756 are formedand the whole structure is back filled with an oxide fill 758, such assilicon dioxide, and planarized. A planarization procedure, such aschemical-mechanical polishing, can be used to provide an even surface.In various embodiments, the conventional sidewall spacers are formedwith silicon nitride.

In FIG. 7D, the sacrificial gate (703 in FIG. 7C) is removed andreplaced by the deposition of a metal layer 760. In various embodiments,the sacrificial gate is removed using a plasma oxidation process.Various deposition processes, such as evaporation, sputtering, chemicalvapor deposition, or atomic layer deposition, may be used to form themetal layer 760. The structure is planarized (not shown) using aplanarization procedure, such as chemical-mechanical polishing,resulting in the self aligned metal gate over the high-κ gate dielectricinsulator 710. Drain and source contacts (not shown) can be formed, aswell as interconnects to other transistors or components, usingconventional techniques. Another heat treatment may occur afterpackaging the integrated circuit in a protective housing in an attemptto minimize the resistivity of the metal gate contacts and other metalinterconnections.

FIGS. 7A-7D illustrate two replacement processes for the formation ofplanar self aligned metal gate transistors, one for disposable sidewallspacers and the other for the gate material itself. The metal gatereplacement technique, as disclosed herein, can be applied to MOSdevices, as generally illustrated in FIGS. 7A-7D, as well as to formmetal floating gates and/or metal control gates in nonvolatile devices.Additionally, various high-κ dielectrics can be used between thefloating gate and the substrate, and between the control gate and thefloating gate in these nonvolatile devices.

FIG. 8 illustrates an embodiment of a method 800 for forming a selfaligned metal gate on high-κ gate dielectrics containing TaSiON.According to various embodiments, a high-κ gate dielectric containingTaSiON is formed on a substrate, at 802. At 804, a sacrificial carbongate is formed on the gate dielectric. At 806, sacrificial carbonsidewall spacers are formed adjacent to the sacrificial carbon gate. At808 source/drain regions for the transistor are formed, using thesacrificial carbon sidewall spacers to define the source/drain regions.The sacrificial carbon sidewall spacers are replaced with non-carbonsidewall spacers at 810. At 812, the sacrificial carbon gate is replacedwith a desired metal gate material to provide the desired metal gatematerial on the gate dielectric.

In various embodiments, source/drain extensions may be formed afterremoving the carbon sidewall spacers and before replacing withnon-carbon sidewall spacers. An etch barrier is used in variousembodiments to separate the sacrificial carbon gate from the sacrificialcarbon sidewall spacers. In various embodiments, the carbon sacrificialgate may be replaced with aluminum (Al), tungsten (W), molybdenum (Mo),gold (Au), silver (Ag), gold alloy, silver alloy, copper (Cu), platinum(Pt), rhenium (Re), ruthenium (Ru), rhodium (Rh), nickel (Ni), osmium(Os), palladium (Pd), iridium (Ir), cobalt (Co), germanium (Ge), ormetallic nitrides such as WN, TiN or TaN covered by metals. The high-κgate dielectric formed at 802 may be one of a number of high-κ gatedielectrics containing TaSiON.

In various embodiments, construction of an integrated circuit structureincludes a dielectric containing TaSiON on which is disposed aself-aligned metal electrode. Additional information regarding aself-aligned metal electrode used as a transistor gate can be found inU.S. patent application Ser. No. 11/216,375, filed 31 Aug. 2005,entitled “SELF ALIGNED METAL GATES ON HIGH-K DIELECTRICS,” which isherein incorporated by reference.

Device Structures

FIG. 9 illustrates an embodiment of a wafer 940 containing integratedcircuits having one or more dielectric layers that include a tantalumsilicon oxynitride film. Conductive electrodes may be disposed on suchdielectrics in a number of configurations such as capacitors,transistors, or elements of a memory. The conductive electrodes may bemetal electrodes, conductive metal nitride electrodes, and/or conductivemetal oxide electrodes. The conductive electrodes may be atomic layerdeposited electrodes. Metal electrodes may be metal substitutedelectrodes and/or self aligned metal electrodes formed in accordancewith the teachings of embodiments discussed herein. A common wafer sizeis 8 inches in diameter. However, wafers are capable of being fabricatedin other sizes, and embodiments of wafers containing a tantalum siliconoxynitride film are not limited to a particular size. A number of diescan be formed on a wafer. A die 941 is an individual pattern on asubstrate that contains circuitry to perform a specific function. Asemiconductor wafer typically contains a repeated pattern of such diescontaining the same functionality. A die is typically packaged in aprotective casing (not shown) with leads extending therefrom (not shown)providing access to the circuitry of the die for communication andcontrol.

Applications containing electronic devices having dielectric layerscontaining tantalum silicon oxynitride film include electronic systemsfor use in memory modules, device drivers, power modules, communicationmodems, processor modules, and application-specific modules, which mayinclude multilayer, multichip modules. Such dielectric layers may beconfigured as multiple layers containing at least one layer of TaSiON orconfigured substantially as a TaSiON layer. In addition, such dielectriclayers may be configured in contact with a metal electrode. Suchcircuitry can be a subcomponent of a variety of electronic systems, suchas a clock, a television, a cell phone, a personal computer, anautomobile, an industrial control system, an aircraft, and others.

FIG. 10 shows an embodiment of a transistor 1000 having a dielectriclayer 1040 containing a TaSiON_(x) film. In an embodiment, transistor1000 includes a source region 1020 and a drain region 1030 in asilicon-based substrate 1010 where source and drain regions 1020, 1030are separated by a body region 1032. Body region 1032 defines a channelhaving a channel length 1034. In an embodiment, a gate dielectric 1040is disposed on substrate 1010 with gate dielectric 1040 formed as adielectric layer containing TaSiON_(x). In an embodiment, gatedielectric 1040 is realized as a dielectric layer formed substantiallyof TaSiON_(x). In an embodiment, gate dielectric 1040 is constructed asmultiple dielectric layers, that is, as a dielectric stack, containingat least one TaSiON_(x) film and one or more layers of insulatingmaterial other than tantalum silicon oxynitride film. In an embodiment,the TaSiON_(x) film is structured as one or more monolayers. Anembodiment of a TaSiON_(x) film is formed using atomic layer deposition.In an embodiment, gate dielectric 1040 may be realized as a gateinsulator in a silicon-based structure.

In an embodiment, a gate 1050 is formed on and contacts gate dielectric1040. In an embodiment, gate 1050 includes conductive material. In anembodiment, gate 1050 includes a conductive material structured as oneor more monolayers. In an embodiment, the conductive material layer isan ALD conductive material layer. In an embodiment, the conductivematerial layer is a substituted metal layer. In an embodiment, theconductive material layer is a self-aligned metal layer. In anembodiment, the thickness of the conductive layer ranges from amonolayer to thousands of angstroms or more.

An interfacial layer may form between body region 1032 and gate adielectric 1040. In an embodiment, an interfacial layer is limited to arelatively small thickness compared to gate dielectric 1040, or to athickness significantly less than gate dielectric 1040 as to beeffectively eliminated. In an embodiment, forming the substrate and thesource and drain regions is performed using standard processes known tothose skilled in the art. In an embodiment, the sequencing of thevarious elements of the process for forming a transistor is conductedwith fabrication processes known to those skilled in the art. In anembodiment, transistor 1000 is a MOSFET transistor. In an embodiment,transistor 1000 is a germanium MOSFET structure. In an embodiment,transistor 1000 is a silicon MOSFET structure. In an embodiment,transistor 1000 is a silicon-germanium (SiGe) MOSFET structure. In anembodiment, transistor 1000 is a gallium arsenide MOSFET structure. Inan embodiment, transistor 1000 is a NMOS transistor. In an embodiment,transistor 1000 is a PMOS transistor. Transistor 1000 is not limited tothe arrangement illustrated in FIG. 10. For example, transistor 1000 maybe structured as a vertical transistor. In an embodiment, use of a gatedielectric containing tantalum silicon oxynitride is not limited tosilicon-based substrates, but is used with a variety of semiconductorsubstrates.

FIG. 11 shows an embodiment of a floating gate transistor 1100 having adielectric layer containing a TaSiON_(x) film. In an embodiment, theTaSiON_(x) film is structured as one or more monolayers. In anembodiment, the TaSiON_(x) film is formed using atomic layer depositiontechniques. In an embodiment, transistor 1100 includes a silicon-basedsubstrate 1110 with a source 1120 and a drain 1130 separated by a bodyregion 1132. Body region 1132 between source 1120 and drain 1130 definesa channel region having a channel length 1134. Located above body region1132 is a stack 1155 including a gate dielectric 1140, a floating gate1152, a floating gate dielectric 1142 (integrate dielectric 1142), and acontrol gate 1150. An interfacial layer may form between body region1132 and gate dielectric 1140. In an embodiment, such an interfaciallayer is limited to a relatively small thickness compared to gatedielectric 1140, or to a thickness significantly less than gatedielectric 1140 as to be effectively eliminated.

In an embodiment, gate dielectric 1140 includes a dielectric containingan atomic layer deposited TaSiON_(x) film formed in embodiments similarto those described herein. In an embodiment, gate dielectric 1140 isrealized as a dielectric layer formed substantially of TaSiON_(x). In anembodiment, gate dielectric 1140 is a dielectric stack containing atleast one TaSiON_(x) film and one or more layers of other insulatingmaterials.

In an embodiment, floating gate 1152 is formed on and contacts gatedielectric 1140. In an embodiment, floating gate 1152 includesconductive material. In an embodiment, floating gate 1152 is structuredas one or more monolayers. In an embodiment, floating gate 1152 is anALD layer. In an embodiment, floating gate 1152 is a substituted metallayer. In an embodiment, floating gate 1152 is a self-aligned metallayer. In an embodiment, the thickness of the floating gate layer rangesfrom a monolayer to thousands of angstroms or more.

In an embodiment, floating gate dielectric 1142 includes a dielectriccontaining a TaSiON_(x) film. In an embodiment, the TaSiON_(x) film isstructured as one or more monolayers. In an embodiment, the TaSiON_(x)is formed using atomic layer deposition techniques. In an embodiment,floating gate dielectric 1142 is realized as a dielectric layer formedsubstantially of TaSiON_(x). In an embodiment, floating gate dielectric1142 is a dielectric stack containing at least one TaSiON_(x) film andone or more layers of other insulating materials.

In an embodiment, control gate 1150 is formed on and contacts floatinggate dielectric 1142. In an embodiment, control gate 1150 includesconductive material. In an embodiment, control gate 1150 is structuredas one or more monolayers. In an embodiment, the control gate 1150 is anALD layer. In an embodiment, control gate 1150 is a substituted metallayer. In an embodiment, control gate 1150 is a self-aligned metallayer. In an embodiment, the thickness of the control gate layer 1150ranges from a monolayer to thousands of angstroms or more. In anembodiment, control gate 1150 is structured as one or more monolayers.

In an embodiment, both gate dielectric 1140 and floating gate dielectric1142 are formed as dielectric layers containing a TaSiON_(x) filmstructured as one or more monolayers. In an embodiment, control gate1150 and floating gate 1152 are formed as conductive layers. In anembodiment, the control gate 1150 and floating gate 1152 are structuredas one or more monolayers. In an embodiment, control gate 1150 andfloating gate 1152 are ALD layers. In an embodiment, control gate 1150and floating gate 1152 are substituted metal layers. In an embodiment,control gate 1150 and floating gate 1152 are self-aligned metal layers.In an embodiment, gate dielectric 1140, floating gate dielectric 1142,control gate 1150, and floating gate 1152 are realized by embodimentssimilar to those described herein, with the remaining elements of thetransistor 1100 formed using processes known to those skilled in theart. In an embodiment, gate dielectric 1140 forms a tunnel gateinsulator and floating gate dielectric 1142 forms an inter-gateinsulator in flash memory devices, where gate dielectric 1140 andfloating gate dielectric 1142 may include an tantalum silicon oxynitridefilm structured as one or more monolayers. Floating gate transistor 1100is not limited to the arrangement illustrated in FIG. 11. For example,floating gate transistor 1100 may be structured as a verticaltransistor. Such structures are not limited to silicon-based substrates,but may be used with a variety of semiconductor substrates, such as forbut not limited to germanium floating gate transistors, SiGe floatinggate transistors, and gallium arsenide floating gate transistors.

FIG. 12 shows an embodiment of a capacitor 1200 having a dielectriclayer containing a tantalum silicon oxynitride film 1220 and having anelectrode 1230. Embodiments of a tantalum silicon oxynitride film 1220structured as one or more monolayers may also be applied to capacitorsin various integrated circuits, memory devices, and electronic systems.In an embodiment for a capacitor 1200 illustrated in FIG. 12, a methodincludes forming a first conductive layer 1210, forming a dielectriclayer 1220 containing a tantalum silicon oxynitride film structured asone or more monolayers on first conductive layer 1210, and forming asecond conductive layer 1230 on dielectric layer 1220. In variousembodiments, second conductive layer 1230, first conductive layer 1210,or both second and first conductive layers 1230, 1210 are ALD conductivematerial layers, substituted metal layers, self-aligned metal layers, ora combination thereof. In an embodiment, the thickness of the conductivelayer ranges from a monolayer to thousands of angstroms or more.

In an embodiment, dielectric layer 1220, containing a TaSiON_(x) film,and conductive layers 1210, 1220 are formed using various embodimentsdescribed herein. In an embodiment, dielectric layer 1220 is realized asa dielectric layer formed substantially of TaSiON_(x). In an embodiment,dielectric layer 1220 is a dielectric stack containing at least oneTaSiON_(x) film and one or more layers of other insulating materials.Embodiments for a tantalum silicon oxynitride film may include, but arenot limited to, a capacitor in a DRAM and capacitors in analog, radiofrequency (RF), and mixed signal integrated circuits. Mixed signalintegrated circuits are integrated circuits that may operate withdigital and analog signals.

FIG. 13 depicts an embodiment of a dielectric structure 1300 havingmultiple dielectric layers 1305-1, 1305-2 . . . 1305-N, in which atleast one layer is a tantalum silicon oxynitride layer. In anembodiment, layers 1310 and 1320 provide means to contact dielectriclayers 1305-1, 1305-2 . . . 1305-N. In an embodiment, each layer 1310,1320 or both layers are conductive layers. In an embodiment, layers 1310and 1320 are electrodes forming a capacitor. In an embodiment, layer1310 is a body region of a transistor with layer 1320 being a gate. Inan embodiment, layer 1310 is a floating gate electrode with layer 1320being a control gate.

In an embodiment, dielectric structure 1300 includes one or more layers1305-1, 1305-2 . . . 1305-N as dielectric layers other than a TaSiONlayer, where at least one layer is a TaSiON layer. In an embodiment,dielectric layers 1305-1, 1305-2 . . . 1305-N include a SiO layer, a SiNlayer, a TaO layer, a TaN layer, a SiON layer, a TaON layer, or variouscombinations of these layers. In an embodiment, dielectric layers1305-1, 1305-2 . . . 1305-N include an insulating metal oxide layer. Inan embodiment, dielectric layers 1305-1, 1305-2 . . . 1305-N include aninsulating nitride layer. In an embodiment, dielectric layers 1305-1,1305-2 . . . 1305-N include an insulating oxynitride layer. In anembodiment, dielectric layers 1305-1, 1305-2 . . . 1305-N include aninsulating silicate layer.

Various embodiments for a dielectric layer containing a tantalum siliconoxynitride film structured as one or more monolayers may provide forenhanced device performance by providing devices with reduced leakagecurrent. Such improvements in leakage current characteristics may beattained by forming one or more layers of a tantalum silicon oxynitridein a nanolaminate structure with other metal oxides,non-metal-containing dielectrics, or combinations thereof. Thetransition from one layer of the nanolaminate to another layer of thenanolaminate provides disruption to a tendency for an ordered structurein the nanolaminate stack. The term “nanolaminate” means a compositefilm of ultra thin layers of two or more materials in a layered stack.Typically, each layer in a nanolaminate has a thickness of an order ofmagnitude in the nanometer range. Further, each individual materiallayer of the nanolaminate may have a thickness as low as a monolayer ofthe material or as high as 20 nanometers. In an embodiment, a SiO/TaSiONnanolaminate contains alternating layers of a SiO and TaSiON. In anembodiment, a SiN/TaSiON nanolaminate contains alternating layers of aSiN and TaSiON. In an embodiment, a SiON/TaSiON nanolaminate containsalternating layers of a SiON and TaSiON. In an embodiment, a TaON/TaSiONnanolaminate contains alternating layers of TaON and TaSiON. In anembodiment, a TaO/TaSiON nanolaminate contains alternating layers of TaOand TaSiON. In an embodiment, a TaN/TaSiON nanolaminate containsalternating layers of TaN and TaSiON. In an embodiment, aSiO/SiON/TaON/TaO/TaN/SiN/TaSiON nanolaminate contains variouspermutations of silicon oxide layers, silicon oxynitride layers,tantalum oxynitride layers, tantalum oxide layers, tantalum nitridelayers, silicon nitride layers, and tantalum silicon oxynitride layers.

In an embodiment, the sequencing of the layers in dielectric structure1300 structured as a nanolaminate depends on the application. Theeffective dielectric constant associated with nanolaminate structure1300 is that attributable to N capacitors in series, where eachcapacitor has a thickness defined by the thickness and composition ofthe corresponding layer. In an embodiment, by selecting each thicknessand the composition of each layer, a nanolaminate structure isengineered to have a predetermined dielectric constant. Embodiments forstructures such as nanolaminate structure 1300 may be used asnanolaminate dielectrics in flash memory devices as well as otherintegrated circuits.

In an embodiment, a layer of the nanolaminate structure 1300 is used tostore charge in a flash memory device. The charge storage layer of ananolaminate structure 1300 in a flash memory device may be a siliconoxide layer.

In an embodiment, transistors, capacitors, and other devices includedielectric films containing a layer of a tantalum silicon oxynitridecomposition with an electrode. In an embodiment, the tantalum siliconoxynitride layer is an atomic layer deposited tantalum siliconoxynitride layer. In an embodiment, the electrode is an atomic layerdeposited electrode. In an embodiment, the electrode is a substitutedmetal layer. In an embodiment, the electrode is a self-aligned metallayer. In an embodiment, dielectric films containing a tantalum siliconoxynitride layer with an electrode are implemented into memory devicesand electronic systems including information handling devices. Invarious embodiments, information handling devices include wirelesssystems, telecommunication systems, and computers. In variousembodiments, such electronic devices and electronic apparatus arerealized as integrated circuits.

FIG. 14 illustrates a block diagram for an electronic system 1400 withone or more devices having a dielectric structure including a TaSiON_(x)film with an electrode. Electronic system 1400 includes a controller1405, a bus 1415, and an electronic device 1425, where bus 1415 provideselectrical conductivity between controller 1405 and electronic device1425. In various embodiments, controller 1405 includes an embodiment ofa TaSiON_(x) film with an electrode. In various embodiments, electronicdevice 1425 includes an embodiment of a TaSiON_(x) film with anelectrode. In various embodiments, controller 1405 and electronic device1425 include embodiments of a TaSiON_(x) film with an electrode. In anembodiment, electronic system 1400 includes, but is not limited to,fiber optic systems, electro-optic systems, and information handlingsystems such as wireless systems, telecommunication systems, andcomputers.

FIG. 15 depicts a diagram of an embodiment of a system 1500 having acontroller 1505 and a memory 1525. In an embodiment, controller 1505includes a TaSiON film with an electrode. In an embodiment, memory 1525includes a TaSiON film structured as one or more monolayers with anelectrode. In an embodiment, controller 1505 and memory 1525 eachinclude a TaSiON film with an electrode. In an embodiment, system 1500also includes an electronic apparatus 1535 and a bus 1515, where bus1515 provides electrical conductivity between controller 1505 andelectronic apparatus 1535 and between controller 1505 and memory 1525.In an embodiment, bus 1515 includes an address bus, a data bus, and acontrol bus, each independently configured. In an alternativeembodiment, bus 1515 uses common conductive lines for providing one ormore of address, data, or control, the use of which is regulated bycontroller 1505. In an embodiment, electronic apparatus 1535 isadditional memory configured in a manner similar to memory 1525. In anembodiment, additional peripheral device or devices 1545 are coupled tobus 1515. In an embodiment, peripheral devices 1545 include displays,additional storage memory, or other control devices that may operate inconjunction with controller 1505. In an alternative embodiment,peripheral devices 1545 may include displays, additional storage memory,or other control devices that may operate in conjunction with memory1525, or controller 1505 and memory 1525. In an embodiment, controller1505 is a processor. In an embodiment, one or more of controller 1505,memory 1525, bus 1515, electronic apparatus 1535, or peripheral devices1545 include an embodiment of a dielectric layer having a TaSiON filmstructured as one or more monolayers with an electrode. In anembodiment, system 1500 includes, but is not limited to, informationhandling devices, telecommunication systems, and computers.

In an embodiment, memory 1525 is realized as a memory device containinga TaSiON film structured as one or more monolayers with an electrode. Inan embodiment, a TaSiON structure with a conductive layer is formed in amemory cell of a memory array. In an embodiment, such a structure isformed in a capacitor in a memory cell of a memory array. In anembodiment, such a structure is formed in a transistor in a memory cellof a memory array. In an embodiment, it will be understood thatembodiments are equally applicable to any size and type of memorycircuit and are not intended to be limited to a particular type ofmemory device. Memory types include a DRAM, SRAM (Static Random AccessMemory) or Flash memories. Additionally, the DRAM could be a synchronousDRAM commonly referred to as SGRAM (Synchronous Graphics Random AccessMemory), SDRAM (Synchronous Dynamic Random Access Memory), SDRAM II, andDDR SDRAM (Double Data Rate SDRAM), as well as other emerging DRAMtechnologies.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement that is calculated to achieve the same purpose maybe substituted for the specific embodiments shown. It is to beunderstood that the above description is intended to be illustrative,and not restrictive, and that the phraseology or terminology employedherein is for the purpose of description and not of limitation.Combinations of the above embodiments and other embodiments will beapparent to those of skill in the art upon studying the abovedescription.

1. An electronic device comprising: a substrate; a dielectric disposedon the substrate, the dielectric including Ta_(x)Si_(y)O_(z)N_(r) (x, y,z, r>0) structured as an arrangement of one or more monolayers; and ametal on and contacting the dielectric.
 2. The electronic device ofclaim 1, wherein the dielectric consists essentially of theTa_(x)Si_(y)O_(z)N_(r).
 3. The electronic device of claim 1, wherein theelectronic device includes contacts to couple the electronic device toother apparatus of a system.
 4. The electronic device of claim 1,wherein the metal includes one or more of aluminum, tungsten,molybdenum, gold, silver, a gold alloy, a silver alloy, copper,platinum, rhenium, ruthenium, rhodium, nickel, osmium, palladium,iridium, cobalt, germanium, WN, TiN, TaN, or a metal nitride other thanWN, TiN, and TaN.
 5. The electronic device of claim 1, wherein thetantalum silicon oxynitride is structured as a film doped with elementsor compounds other than silicon, tantalum, oxygen, and nitrogen.
 6. Theelectronic device of claim 1, wherein the dielectric includes one ormore of Si_(a)O_(b), Si_(c)N_(d), Ta_(e)O_(f), Ta_(g)N_(h),Si_(k)O_(l)N_(m), or Ta_(n)O_(p)N_(q) (a, b, c, d, e, f, g, h, k, l, m,n, p, and q>0) in addition to the Ta_(x)Si_(y)O_(z)N_(r).
 7. Theelectronic device of claim 1, wherein the dielectric includes one ormore of an insulating metal oxide, an insulating nitride, an insulatingoxynitride, or an insulating silicate.
 8. The electronic device of claim1, wherein the dielectric is structured as nanolaminate.
 9. Theelectronic device of claim 8, wherein the nanolaminate includesalternating layers of silicon oxide and tantalum silicon oxynitride oralternating layers of silicon nitride and tantalum silicon oxynitride oralternating layers of silicon oxynitride and tantalum silicon oxynitrideor alternating layers of tantalum oxynitride and tantalum siliconoxynitride or alternating layers of tantalum oxide and tantalum siliconoxynitride or alternating layers of tantalum nitride and tantalumsilicon oxynitride.
 10. The electronic device of claim 8, wherein thenanolaminate includes a permutation of silicon oxide layers, siliconoxynitride layers, tantalum oxynitride layers, tantalum oxide layers,tantalum nitride layers, silicon nitride layers, and tantalum siliconoxynitride layers.
 11. The electronic device of claim 1, wherein thedielectric is structured as a capacitor dielectric in a capacitor. 12.The electronic device of claim 1, wherein the dielectric is structuredas a tunnel gate insulator in a floating gate transistor.
 13. Theelectronic device of claim 12, wherein the floating gate transistor isstructured as a vertical transistor.
 14. A wafer comprising: a repeatedpattern of dice on a substrate, each die having an electronic device,the electronic die including a dielectric disposed on the substrate, thedielectric including Ta_(x)Si_(y)O_(z)N_(r) (x, y, z, r>0) structured asan arrangement of one or more monolayers; and a metal on and contactingthe dielectric.
 15. The wafer of claim 14, wherein the substrateincludes a silicon substrate, a silicon germanium substrate, a germaniumsubstrate, a gallium arsenide substrate, or as silicon-on-sapphiresubstrate.
 16. The wafer of claim 14, wherein the electronic deviceincludes a memory array.
 17. An electronic apparatus comprising: anarray of memory cells on a substrate, each memory cell including adielectric having Ta_(x)Si_(y)O_(z)N_(r) (x, y, z, r>0) structured as anarrangement of one or more monolayers; and a metal on and contacting thedielectric.
 18. The electronic apparatus of claim 17, wherein thedielectric and the metal are structured as a capacitor in each memorycell.
 19. The electronic apparatus of claim 17, wherein the dielectricand the metal are structured in a floating gate transistor in eachmemory cell.
 20. The electronic apparatus of claim 17, wherein thedielectric is structured as a nanolaminate to store charge in a flashmemory device.
 21. The electronic apparatus of claim 20, wherein thenanolaminate has a charge storage layer to store the charge, the chargestorage layer including silicon oxide.